1. Field of the Invention
The present invention is generally directed to a fan. Particularly, the present invention is directed to an air circulation fan having a shroud for enhancing fan performance.
2. Description of the Related Art
Electric fans for circulating air are widely used in commercial and industrial environments. For example, air circulation fans are commonly located at each work station in factories, such as automobile plants. In the past, operation of air circulation fans has generated a considerable amount of noise. The primary source of noise during the operation of such fans is the interaction of the tip region of each blade with moving air generated by operation of the fan. Reduction in noise levels caused by the operation of an air circulation fan is therefore desired, particularly in those environments in which a large number of such fans are utilized.
Air circulation fans have previously not been used in agricultural settings for a variety of reasons. Most notably, in agricultural settings, such as poultry barns, it is desirable to use fans which can disperse unclean air at high flow rates. Conventional air circulation fans, which utilize traditional front and rear fan guard members in the form of a grille, do not produce these desired results, and have thus been unsatisfactory for use in a poultry barn. Accordingly, box-type fans, which have a closed structure and a venturi surrounding the periphery of the fan propeller, have been widely used in agricultural settings. Box-type fans operating under adverse static pressures can produce a flow of air having a cfm valve. A distinct disadvantage, however, is that the inlet flow field pattern is purely axial which results in stagnant flow regions in areas upstream and adjacent to the fan itself. The need exists for a fan which enhances air circulation without significantly increasing the cost of the fan and noise levels as well as the complexity of its manufacture. Additionally, the need exists for an air circulator fan which is useful in an agricultural setting, such as a poultry barn. The present invention meets these needs while overcoming the drawbacks of the prior art.